Systems and methods for multi-channel transceiver communications

ABSTRACT

Systems and methods for transceiver communication are discussed herein. A filter module may be configured to filter each carrier signal of a multicarrier transmit signal with a different bandpass filter, each bandpass filter configured to filter a different frequency band. A carrier control module may be configured to control the plurality of bandpass filters of the filter module using a carrier selection signal to enable or disable each bandpass filter, thereby coupling carrier signals of the multicarrier transmit signal to a first set of bandpass filters and decoupling a second set of bandpass filters. Filtering the carrier signals of the multicarrier transmit signal is performed by the first set of bandpass filters while the decoupling of the second set of bandpass filters limits energy in the respective frequency band. An antenna may be configured to transmit the filtered multicarrier transmit signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/771,017, filed Feb. 19, 2013 and entitled “Systems andMethods for Multi-Channel Transceiver Communications,” which claims thebenefit of U.S. Provisional Patent Application Ser. No. 61/599,631,filed Feb. 16, 2012 and entitled “Multi-Signal, Multi-ChannelSeparator,” which are incorporated by reference herein.

U.S. patent application Ser. No. 13/771,017 is a continuation-in-part ofU.S. patent application Ser. No. 13/455,986, filed Apr. 25, 2012 andentitled “Systems and Methods for Reduction of Triple Transit Effects inTransceiver Communications,” now U.S. Pat. No. 8,983,400, which claimsthe benefit of U.S. Provisional Patent Application Ser. No. 61/478,896,filed Apr. 25, 2011 and entitled “Diplexers with Voltage VariableAttenuators for Reducing Triple Transit Effect in Coaxial CableTransmission Systems,” which are incorporated by reference herein.

U.S. patent application Ser. No. 13/771,017 is also acontinuation-in-part of U.S. patent application Ser. No. 13/740,087,filed Jan. 11, 2013 and entitled “Systems and Methods for Improved HighCapacity in Wireless Communication Systems,” now U.S. Pat. No.8,842,788, which is a continuation-in-part of U.S. patent applicationSer. No. 13/654,294, filed Oct. 17, 2012 and entitled “Systems andMethods for Signal Frequency Division in Wireless CommunicationSystems,” now U.S. Pat. No. 9,008,162, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/548,063, filed Oct. 17, 2011and entitled “Combination of Main, Diversity and Cross Polar Signals onOne Coax Cable,” which are incorporated by reference herein. U.S. patentapplication Ser. No. 13/740,087 also claims the benefit of U.S.Provisional Patent Application Ser. No. 61/585,624, filed Jan. 11, 2012and entitled “Microwave Radios with Improved High CapacityImplementation,” which is incorporated by reference herein.

BACKGROUND

1. Field of the Invention(s)

The present invention(s) generally relate to transceiver communications.More particularly, the invention(s) relate to systems and methods formulti-channel transceiver communications.

2. Description of Related Art

In microwave radio systems, a transceiver may include an indoor unit(IDU) and an outdoor unit (ODU) coupled to an antenna. In one example,the IDU may be coupled to a server or other computer over a wirednetwork (e.g., LAN, WAN, or the Internet). Information to be wirelesslytransmitted may be prepared by both the IDU and the ODU before wirelesstransmission. Similarly, the outdoor unit may receive signals from theantenna to provide to the server or other computer via the IDU.

The IDU and the ODU have typically been coupled to each other over acoaxial cable. Signals may be sent from the IDU to the ODU, for example,using frequency diversity to avoid colliding with signals being providedby the ODU to the IDU. In order to maintain the signals, complex filtersare required by both the IDU and the ODU to separate out the differentfrequencies (e.g., 125 MHz from 311 MHz). Further, filters are requiredto reduce or eliminate triple transit influences caused by a mismatch ofcables to filters or other components. As a result of triple transitinfluences, data propagated across the cable from the IDU to the ODU maybounce back to the IDU causing self interference which may degradeperformance of the radio.

SUMMARY OF THE INVENTION

Systems and methods for transceiver communication are discussed herein.An exemplary system comprises a first transceiver unit comprising afirst attenuator, a filter module, a gain module, and an antenna. Thefirst attenuator may be configured to attenuate a transmission signalfrom a second transceiver module over a coaxial cable. The transmissionsignal may comprise a primary component and a triple transit component.The first attenuator may further be configured to attenuate and providea reflection signal over the coaxial cable to the second transceivermodule. The reflection signal may be based on a reflection of at least aportion of the transmission signal. The filter module configured tofilter the transmission signal. The gain module may be configured toincrease the gain of the transmission signal from the filter. Theantenna may be configured to transmit the transmission signal. Thetriple transit component may comprise at least a portion of thereflection signal reflected from the second transceiver module over thecoaxial cable.

In various embodiments, the system may further comprise a sensor and acontroller. The sensor may be configured to provide a sensor signalbased on the transmission signal. The controller may be configured tocompare the sensor signal to an attenuation threshold, to generate anattenuator control signal based on the comparison, and to control thefirst attenuator with the attenuator control signal. The controller maybe further configured to compare the sensor signal to a gain threshold,to generate a gain control signal based on the comparison of the sensorsignal and the gain threshold, and to control the gain module with thegain control signal. In some embodiments, the controller may be furtherconfigured to generate a gain control signal based on the comparison ofthe sensor signal and the attenuator threshold, and to control the gainmodule with the gain control signal.

The system may further comprise a waveguide filter and a waveguide. Thewaveguide filter may be configured to filter the transmission signal.The waveguide may be configured to provide the filtered transmissionsignal to the antenna.

In some embodiments, the second transceiver module comprises a secondattenuator configured to attenuate the reflection signal from the firsttransceiver module over the coaxial cable.

Another exemplary system comprises a first transceiver module whichincludes a first attenuator, a filter module, a gain module, and amodem. The first attenuator may be configured to attenuate a receivesignal from a second transceiver module over a coaxial cable. Thereceive signal may comprise a primary component and a triple transitcomponent. The first attenuator may be further configured to attenuateand provide a reflection signal over the coaxial cable to the secondtransceiver module. The reflection signal may be based on a reflectionof at least a portion of the transmission signal. The filter module maybe configured to filter the receive signal. The gain module may beconfigured to increase the gain of the receive signal. The modem may beconfigured to demodulate the receive signal and provide informationassociated with the demodulated receive signal to a digital device.

The system may further comprise a sensor and a controller. The sensormay be configured to provide a sensor signal based on the receivesignal. The controller may be configured to compare the sensor signal toan attenuation threshold, to generate an attenuator control signal basedon the comparison, and to control the attenuator with the attenuatorcontrol signal. The controller may be further configured to compare thesensor signal to a gain threshold, to generate a gain control signalbased on the comparison of the sensor signal and the gain threshold, andto control the gain module with the gain control signal. In someembodiments, the controller is further configured generate a gaincontrol signal based on the comparison of the sensor signal and theattenuator threshold, and to control the gain module with the gaincontrol signal.

The second transceiver module may comprise an antenna, a waveguide, anda waveguide filter. The antenna may be configured to receive the receivesignal. The waveguide filter may be configured to filter the signalreceived from the waveguide prior to the second transceiver moduleproviding the receive signal over the coaxial cable to the firsttransceiver module.

In some embodiments, the second transceiver module comprises a secondattenuator configured to attenuate the reflection signal from the firsttransceiver module over the coaxial cable.

An exemplary method may comprise receiving, from a second transceivermodule via a coaxial cable, a transmission signal, the transmissionsignal comprising a primary component and a triple transit component,attenuating, by a first attenuator, the transmission signal,attenuating, by the first attenuator, a reflection signal, thereflection signal being based on a reflection of at least a portion ofthe transmission signal, providing the reflection signal to the secondtransceiver module via the coaxial cable, adjusting, after attenuationby the first attenuator, the gain of the transmission signal, andtransmitting the transmission signal by an antenna.

In various embodiments, the method may further comprise generating asensor signal based on the transmission signal, comparing the sensorsignal to an attenuation threshold, generating an attenuator controlsignal based on the comparison, and controlling the attenuation of thetransmission signal with the attenuator control signal. Further, themethod may further comprise comparing the sensor signal and a gainthreshold, generating a gain control signal based on a comparison of thesensor signal and the gain threshold, and controlling the gainadjustment of the transmission signal based on the gain control signal.In some embodiments, the method further comprises generating a gaincontrol signal based on a comparison of the sensor signal and theattenuation threshold and controlling the gain adjustment of thetransmission signal based on the gain control signal.

In some embodiments, the method may further comprise filtering thetransmission signal with a waveguide filter and providing, with awaveguide, the filtered transmission signal to the antenna. The methodmay comprise attenuating, by the second transceiver module, thereflection signal from the first transceiver module over the coaxialcable.

Another exemplary method comprises receiving, from a second transceivermodule via a coaxial cable, a receive signal, the receive signalcomprising a primary component and a triple transit component,attenuating, by a first attenuator, the receive signal, attenuating, bythe first attenuator, a reflection signal, the reflection signal beingbased on a reflection of at least a portion of the transmission signal,providing the reflection signal to the second transceiver module via thecoaxial cable, adjusting, after attenuation by the first attenuator, thegain of the transmission signal, demodulating the receive signal, andproving information from the demodulated signal to a digital device.

The method may further comprise generating a sensor signal based on thereceive signal, comparing the sensor signal to an attenuation threshold,generating an attenuator control signal based on the comparison, andcontrolling the attenuation of the receive signal with the attenuatorcontrol signal. In some embodiments, the method may further comprisecomparing the sensor signal and a gain threshold, generating a gaincontrol signal based on a comparison of the sensor signal and the gainthreshold, and controlling the gain adjustment of the receive signalbased on the gain control signal. In various embodiments, the method mayfurther comprise generating a gain control signal based on a comparisonof the sensor signal and the attenuator threshold and controlling thegain adjustment of the receive signal based on the gain control signal.

The method may comprise providing the receive signal from an antennaassociated with the second transceiver module and filtering, with awaveguide filter, the transmission signal received from the antenna viaa waveguide prior to receiving, from the second transceiver module viathe coaxial cable, the receive signal.

In various embodiments, the method further comprises attenuating, by thesecond transceiver module, the reflection signal from the first.

Systems and methods for transceiver communication are discussed herein.An exemplary system may comprise a filter module, a carrier controlmodule, and an antenna. The filter module may be configured to filtereach carrier signal of a multicarrier transmit signal with a differentbandpass filter, each bandpass filter configured to filter a differentfrequency band. The carrier control module may be configured to controlthe plurality of bandpass filters of the filter module using a carrierselection signal to enable or disable each bandpass filter, therebycoupling carrier signals of the multicarrier transmit signal to a firstset of bandpass filters and decoupling a second set of bandpass filters.Filtering the carrier signals of the multicarrier transmit signal isperformed by the first set of bandpass filters while the decoupling ofthe second set of bandpass filters limits energy in the respectivefrequency band. The antenna may be configured to transmit the filteredmulticarrier transmit signal. 2. The system of claim 1, furthercomprising a second transceiver module comprising the modulation module,the second transceiver module configured to provide the multicarriertransmit signal to the filter module of the first transceiver moduleover a cable.

The first transceiver module may be further configured to receive atleast one receive signal from the antenna and provide the receive signalto the second transceiver module over the cable. The carrier signals ofthe multicarrier transmit signal may be at different frequencies thanthe at least one receive signal. The first transceiver module mayfurther comprise an nplexer configured to receive the multicarriertransmit signal and the carrier selection signal from the secondtransceiver module.

In some embodiments, the unused carriers of the multicarrier transmitsignal include thermal noise. Further, in some embodiments, decouplingof the second set of bandpass filters attenuates the thermal noise. Thefilter module may further comprise a plurality of switches, each of theswitches coupled to at least one of the plurality of bandpass filters.The control of the plurality of bandpass filters of the filter moduleusing the carrier selection signal to enable or disable each bandpassfilter of the plurality of bandpass filters may comprise the carriercontrol module being configured to control at least one of the pluralityof switches to enable or disable at least one bandpass filter of theplurality of bandpass filters.

The first transceiver module may further comprise an attenuation moduleconfigured to attenuate signals received from the second transceivermodule as well as reflected signals thereby enabling the reduction oftriple transit effect.

An exemplary method may comprise receiving a carrier selection signal,controlling a plurality of bandpass filters of a filter module using thecarrier selection signal to enable or disable each bandpass filter ofthe plurality of bandpass filters, each bandpass filter of the pluralityof bandpass filters configured to filter a different frequency band,receiving a multicarrier transmit signal from a modulation module,filtering each carrier signal of the multicarrier transmit signal with adifferent bandpass filter of the plurality of bandpass filters, disabledbandpass filters limiting energy of the multicarrier transmit signal inthe respective frequency band, and transmitting, by an antenna, thefiltered carrier signals of the multicarrier transmit signal using anantenna.

Another exemplary system may comprise a first transceiver module. Thefirst transceiver module may comprise a means for filtering, a carriercontrol module, and an antenna. The means for filtering configured tofilter each carrier signal of a multicarrier transmit signal by adifferent bandpass filter of a plurality of bandpass filters, eachbandpass filter of the plurality of bandpass filters configured tofilter a different frequency band, the multicarrier transmit signalbeing from a modulation module. The carrier control module may beconfigured to receive a carrier selection signal and control theplurality of bandpass filters of the filter module using the carrierselection signal to enable or disable each bandpass filter of theplurality of bandpass filters thereby coupling carrier signals of themulticarrier transmit signal to a first set of bandpass filters anddecoupling a second set of bandpass filters, filtering the carriersignals of the multicarrier transmit signal is performed by the firstset of bandpass filters while the decoupling of the second set ofbandpass filters limits energy in the respective frequency band. Theantenna may be configured to transmit the filtered carrier signals ofthe multicarrier transmit signal using an antenna.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an environment including two transceiver units in someembodiments.

FIG. 2 is a block diagram of a portion of an outdoor unit (ODU) in someembodiments.

FIG. 3 depicts another transmitting radio frequency unit in someembodiments.

FIG. 4 is a block diagram of a portion of an indoor unit (IDU) in someembodiments.

FIG. 5 is a flow diagram for a method of reducing noise between twotransceiver units in some embodiments.

FIG. 6 is a flow diagram for configuring an attenuator module and a gainmodule to reduce noise in transceiver communications in someembodiments.

FIG. 7 is a block diagram of a portion of an outdoor unit (ODU) in someembodiments.

FIG. 8 is a flow chart for processing receive signals and a transmitsignal in a transceiver unit in some embodiments.

FIG. 9 is a flow chart for filtering signals from a multicarriertransmit signal in some embodiments.

FIG. 10 is an exemplary FCC operation bandpass filter in someembodiments.

FIG. 11 is an exemplary ETSI operation bandpass filter in someembodiments.

FIG. 12 is an exemplary multi-carrier operation bandpass filter in someembodiments.

FIG. 13 is a depiction of a multicarrier transmit signal that may befiltered by the multi-carrier operation bandpass filter identified inFIG. 12 in some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

In various embodiments, a first module of a transceiver unit (e.g., anIDU) may communicate with a second module of the transceiver unit (e.g.,an ODU) over one or more coaxial cables. One or more attenuator modulesmay attenuate reflected signals between the two units thereby reducingnoise caused by reflected signals (i.e., the triple transit effect). Insome embodiments, portions of signals that are reflected between the twotransceiver units may be attenuated at each reflection thereby reducingthe strength of the reflected signal. Since the desired information(e.g., the transmission signal from the IDU or the receive signal fromthe ODU) may only be attenuated once or twice, multiple instances ofattenuating the reflected signal may significantly reduce the noisecaused by the triple transit effect relative to the desired signal.

In one example, an IDU may provide an initial transmission signal over acoaxial cable to an ODU. An attenuator module of the ODU may receive andattenuate the initial transmission signal. Subsequently, a component ofthe initial transmission signal may be reflected by one or morecomponents of the ODU. The reflected signal is also attenuated by theattenuator module before propagating back down the coaxial cable to theIDU. A portion of the reflection signal may, again, be reflected back tothe ODU whereby the attenuator module, again, attenuates the signal. Asa result, even if the reflected signal is mixed with new transmissionsignals from the IDU, the reflected signal will have been separatelyattenuated three or more different times thereby reducing the impact ofthe reflected signal.

Those skilled in the art will appreciate that any number of signals maybe reflected between the IDU and the ODU over time. The process ofattenuating the reflected signals upon each reflection reduces theenergy of the undesired signal thereby reducing or eliminating thetriple transit effect without expensive components or sophisticatedtuning.

FIG. 1 is an environment 100 including two transceiver units 102 and 104in some embodiments. Each of the transceiver units 102 and 104 are splitmount radios. A split-mount radio has a part of the electronics mountedoutdoors with an antenna and part indoors. The outdoor unit (ODU) may bethe RF transmitter/receiver. The indoor unit (IDU) contains themodulator/demodulator, multiplexer, control, and traffic interfaceelements. The IDU and ODU may be coupled together using a cable. Bycomparison, an all-indoor radio has all radio equipment installed insideand is connected to its antenna using a waveguide or coax feeder. Asplit-mount radio may be a point-to-point radio installation forlicensed 6 to 38+ GHz frequency bands with the ODU direct-mounted to therear of the antenna to provide an integral antenna feed. By having theODU mounted with the antenna, split-mount may eliminate or reduce feederlosses, minimize or reduce rack occupancy, and/or lower installed costscompared to indoor radios.

For example, transceiver unit 102 may comprise an indoor unit (IDU) 108in communication with a processor and/or a digital device, an outdoorunit (ODU) 110 in communication with the IDU 108 over cables 118, awaveguide 112 in communication with the ODU 110, and an antenna 116. TheIDU 108 may comprise a modulator/demodulator and control circuitry forproviding data from a digital device or a processor over line 114 to theantenna 116 via the ODU 110 and/or the waveguide 112. Similarly, the IDU108 may also be configured to receive information from the antenna 116via the ODU 110 for providing to the digital device or processor via theline 114. The ODU 110 may comprise an RF transmitter/receiver and becoupled with the antenna 116. The waveguide 112 may or may not be a partof the ODU 110.

The IDU 108 of the transceiver unit 102 may be coupled to the ODU 110utilizing a coaxial cable 118. Although only one coaxial cable 118 isdepicted in FIG. 1, any number of coaxial cables may provide signalsbetween the IDU 108 and the ODU 110. Further, those skilled in the artwill appreciate that any number and/or type of cables may be configuredto receive and transmit signals between the IDU 108 and the ODU 110.

Similarly, transceiver unit 104 may comprise an IDU 120 in communicationwith a processor and/or a digital device, an ODU 122 in communicationwith the IDU 120 over cable 130, a waveguide 124 in communication withthe ODU 122, and an antenna 128. The IDU 120 may comprise amodulator/demodulator and control circuitry for providing data from adigital device or a processor over line 126 to the antenna 128 via theODU 122 and/or the waveguide 124. Similarly, the IDU 120 may also beconfigured to receive information from the antenna 128 via the ODU 122for providing to the digital device or processor via the line 126. TheODU 122 may comprise an RF transmitter/receiver and be coupled with theantenna 128. The waveguide 124 may or may not be a part of the ODU 122.

The IDU 120 of the transceiver unit 104 may be coupled to the ODU 122utilizing a coaxial cable 130. Although only one coaxial cable 130 isdepicted in FIG. 1, any number of coaxial cables may provide signalsbetween the IDU 108 and the ODU 110. Further, those skilled in the artwill appreciate that any number and/or type of cables may be configuredto receive and transmit signals between the IDU 108 and the ODU 110.

In various embodiments, the IDU 108 communicates with the ODU 110 viaone or more coaxial cables. During transmission, information receivedvia the line 114 may be modulated and provided over the coaxial cables118 to the ODU 110. The ODU 110 may attenuate the signal from the IDU108. A portion of the signal from the IDU 108 may be reflected back tothe IDU 108 whereby the reflected signal may again be attenuated. Theremaining un-reflected portion of the signal received by the ODU 110from the IDU 108 may be filtered, and gain adjusted before beingprocessed to be transmitted over the antenna 116 via the waveguide 112.Those skilled in the art will appreciate that if a portion of thereflected signal is again reflected by the IDU 108 back to the ODU 110,the reflected signal may again be attenuated. As a result, the desiredsignal may be attenuated once while the undesired reflection signal thatis being reflected back and forth between the IDU 108 and the ODU 110may be attenuated three or more times.

During reception of information, the ODU 110 may receive a receivesignal from the antenna 116 via the waveguide 112. The ODU 110 mayprovide the receive signal over the coaxial cable 118 to the IDU 108.Subsequently, the IDU 108 may attenuate the signal from the ODU 110. Aportion of the signal from the IDU 108 may be reflected back to the ODU110 whereby the reflected signal may again be attenuated. The remainingun-reflected portion of the signal received by the IDU 108 from the ODU110 may be filtered, and gain adjusted before being modulated to provideinformation to a digital device, memory, or processor via line 114.

Those skilled in the art will appreciate that the transceiver unit 104may perform in a manner similar to the transceiver 102. In variousembodiments, the two transceiver units 102 and 104 may be incommunication with each other over a wireless communication tower 106.Those skilled in the art will appreciate that the transceiver units 102and 104, individually or together, may communicate with any digitaldevice or receiver.

The wireless communication tower 106 (e.g., cell tower or othermicrowave radio device) may be any device configured to receive and/ortransmit wireless information.

FIG. 2 is a block diagram of a portion of an outdoor unit (ODU) 110 insome embodiments. In some embodiments, a diplexer may split or combinetwo frequencies. This diplexer may include two or more filters. One ofthe filters may pass a first frequency and reject a second frequency.Another of the filters may pass the second frequency but reject thefirst frequency. Return loss between the transceiver unit and the cablemay need to be reduced or minimized to avoid the triple transit effectwhich is harmful to data transmissions, especially for high speedtransmissions. The triple transit effect on the data transmissionquality may vary depending on the cable type, cable length, data speedand the carrier frequency.

The length of the cable between the two transmission units may affectthe significance of the triple transit effect. For example, for a 350MHz carrier frequency, Belden-9913 cable, the most damage from thetriple transit effect on the data transmission appears to be when thecable is approximately 500 feet long between the two units. For ashorter or longer cable, the effect is diminished because the ratio ofthe transmit signal to the reflected signal may be stronger. Inconventional diplexer designs, fixed value components typically do notsatisfy this demanding requirement due to the tolerance of thecomponents. Tunable lumped elements, such as tunable inductors andcapacitors are often required. However, the tunable components arecostly and the tuning process is both costly and time consuming.

In various embodiments, an attenuator at or near the interface between atransceiver unit and cable may allow the use of fixed value elements andavoid or reduce the tuning process. In one example, a voltage controlledattenuator may improve the return loss of a diplexer. A 1 dB ofattenuation at the attenuator may improve the return loss by 2 dB. As aresult the triple transit effect is reduced. Depending on cable lengthand transmission requirements, the attenuator may be pre-set oradaptively adjusted to minimize the triple transit effect. A gain module(e.g., a variable gain amplifier) may adjust the gain of the signal tomaintain a constant power level to other circuits in the transceivermodule.

In various embodiments, a portion of the ODU 110 comprises an attenuatormodule 204, filter modules 206 and 208, and a gain module 210. The ODU110 may optionally include a controller 212 and a sensor 214. Theattenuator module 204 may be coupled with a cable 202 that passessignals between the ODU 110 and the IDU 108. Filter module 206 mayfilter attenuated non-reflected signals received from the IDU 108. Thefilter module 208 may filter signals received from other components ofthe ODU 110 via the line 218 before providing the signal to theattenuator module 204 for attenuation and transmission to the IDU 108over the cable 202. The gain module 210 may adjust the gain of a signalfrom the filter module 206 before providing the signal to the rest ofthe ODU 110 components via line 216.

In various embodiments, the ODU 110 is a transceiver module configuredto receive signals from the IDU 108 to be processed and provided to anantenna for wireless transmission. The ODU 110 may also receive andprocess signals from the antenna to provide to the IDU 108 over cable202. The signal may ultimately be demodulated and provided to a digitaldevice or the like. A digital device is any device with a processor andmemory.

The attenuator module 204 may comprise an attenuator configured toattenuate a signal. In various embodiments, the attenuator module 204attenuates signals from the IDU 108 received over the cable 202. Theattenuator module 204 may also attenuate signals received from anantenna and provided to the IDU 108 over the cable 202. The attenuatormodule 204 may, in some embodiments, be voltage controlled or currentcontrolled.

In one example, the attenuator module 204 may attenuate a transmissionsignal from the IDU 108. The transmission signal may be provided by theIDU 108 to be processed and transmitted by a microwave or any RFantenna. The attenuator module 204 may attenuate the transmission signalbefore providing the transmission signal to the diplexer, filtermodules, or any other component. A portion of the transmission signalmay be reflected by one or more components of the ODU 110 (e.g., thediplexer or the filter modules 206 and/or 208). The reflected signal mayagain be attenuated by the attenuator module 204 before the reflectedsignal is transmitted back to the IDU 108 over the cable 202. Thoseskilled in the art will appreciate that the unwanted portion of thesignal has been attenuated twice in this example. If a portion of thereflected signal is reflected by the IDU 108 back to the ODU 110, theattenuator module 204 may attenuate the signal a third time while anynew signals provided by the IDU 108 to be transmitted may be attenuatedonly once. As a result of the multiple attenuations in comparison to thetransmission signal, the reflected portions of the signals lose energyand noise is reduced. The attenuator module 204 may be any kind ofattenuator.

In some embodiments, the ODU 110 comprises a diplexer coupled to filtermodules 206 and 208. The diplexer may provide signals at a firstfrequency from the attenuator module 204 to the filter module 206. Thediplexer may also provide signals at a second frequency from the filtermodule 208 to the attenuator module 204. Those skilled in the art willappreciate that any splitter or switch may be used in place of or inaddition to the diplexer.

The filter modules 206 and 208 may comprise filters configured to filtersignals from the attenuator module 204 or from other circuitry of theODU 110. The filter modules 206 and 208 may comprise many differenttypes of filters (e.g., bandpass filter, low pass filter, high passfilter, or the like) with many different electrical properties. In oneexample, the filter module 206 may be a band pass filter configured tofilter the attenuated transmission signal. The filter module 208 mayalso be a bandpass filter configured to filter a signal from othercomponents of the ODU 110 (e.g., from a downconverter configured todownconvert a signal received from an antenna).

Those skilled in the art will appreciate that each of the filter modules206 and 208 may be the same as one or more other filter modules. Forexample, filters module 206 may kind of filter and the other filter 208may be another kind of filter. In another example, filters module 206and 208 may both be filters of a similar type but have differentelectrical properties. Each filter modules 206 and 208 may include oneor more components. For example, the filter modules 206 may comprise oneor more filters.

In various embodiments, the use of the attenuator module 404 may allowfor one or more broader bandpass filters. Without the attenuator 404,increasing the bandwidth of the bandpass filters may require extensiveor significant tuning of the components of the ODU 110 and/or the IDU108. With the attenuator, significant tuning may not be necessary.

The gain module 210 may comprise one or more amplifiers configured toamplify the signal received from the filter module 206. In variousembodiments, the gain module 210 may be configured to adjust the gain ofthe signal lost in attenuation. The signal from the filter module 206may then be at a proper level for other components of the ODU 110 (seeFIG. 3). The gain module 210 may include any kind of amplifiers and/orattenuators. The gain module 210 may be, for example, voltage controlledor current controlled.

In various embodiments, the ODU 110 may comprise a controller 212configured to calibrate and/or control the attenuator module 204. Insome embodiments, the controller 212 may be configured to calibrateand/or control the gain module 210. The controller 212 may be configuredto detect a desired power level of the transmission signal and correlatethe desired power to the desired level of attenuation. For example, ifthe power level of the transmission signal is too high, then attenuationmay need to increase to ensure that the reflected signals aresufficiently attenuated to reduce or eliminate the impact of the tripletransit effect on the desired transmission signal. Alternately, if thepower level of the transmission signal is too low, then the attenuationmay need to decrease to ensure that a sufficient power level of thetransmission signal is provided to the rest of the ODU 110 (e.g., fortransmission over the antenna).

In one example, the controller 212 receives a sample or other signalrelated to the transmission signal. A sensor 214 may provide the sampleor other signal to the controller 212. The sensor 214 may be any kind ofsensor (e.g., a sampler or the like). The controller may compare thesensor signal from the sensor 214 to one or more attenuator thresholds(e.g., one or more predetermined values). Based on the comparison, thecontroller 212 may generate an attenuator control signal to control theattenuator module 204.

The sensor 214 is depicted in FIG. 2 as being between the filter module206 and the gain module 210. Those skilled in the art will appreciatethat the sensor 214 may be located between the attenuator module 204 andthe filter module 206 or any other position.

In various embodiments, the controller 212 may be configured todetermine an expected strength (e.g., power level) of the sensor signal.If the power level of the sensor signal is within an expected range ofone or more attenuation thresholds (e.g., +/−5% of a single attenuationthreshold), the controller 212 may control the attenuator module 204 tomaintain existing attenuation. In some embodiments, when the desiredattenuation is reached, the controller 212 may not generate anattenuation control signal. If the sensor signal is below a lowattenuation threshold, the controller 212 may control the attenuatormodule 204 to reduce attenuation. If the sensor signal is above a highattenuation threshold, the controller may control the attenuator module204 to increase attenuation.

The controller 212 may also be configured to control the gain module210. In some embodiments, the controller compares the detected power ofthe transmission signal (e.g., the sensor signal) to one or more gainthresholds. If the power level of the sensor signal is within anexpected range of one or more gain thresholds (e.g., +/−7% of a singlegain threshold), the controller 212 may control the gain module 210 tomaintain existing gain adjustment. In some embodiments, when the desiredgain is detected, the controller 212 may not generate a gain controlsignal. If the sensor signal is below a low gain threshold, thecontroller 212 may control the gain module 210 to increase gain. If thesensor signal is above a high gain threshold, the controller may controlthe gain module 210 to decrease gain.

The cable 202 may include any number of cables. In one example, thecable 202 may comprise one or more coaxial cables. The coaxial cable(s)may be any kind of coaxial cable(s). Those skilled in the art willappreciate that any type of cable may be used.

Lines 216 and 218 may be a conductive path (e.g., wire or trace) thatprovides signals to or from other components of the ODU 110.

In various embodiments, signals received from an antenna via the line218 may by filtered by the filter module 208 and provided directly overthe cable 202 without passing through the attenuator module 204. In oneexample, the IDU 108 includes an attenuator that may attenuate thesignal from the filter module 208 (see FIG. 4). In some embodiments, asignal from an antenna may be filtered by the filter module 208 and besubsequently attenuated by the attenuator module 204 before passingthrough the cable 202. The IDU 208 may receive the signal via the cable202 and subsequently attenuate the signal.

In various embodiments, the ODU 110 may not include an attenuator modulebut the IDU 108 may include an attenuator module (see FIG. 4). In someembodiments, both the ODU 110 and the IDU 108 include an attenuator.

It will be appreciated that a “module” may comprise software, hardware,firmware, and/or circuitry. In one example one or more software programscomprising instructions capable of being executable by a processor mayperform one or more of the functions of the modules described herein. Inanother example, circuitry may perform the same or similar functions.Alternative embodiments may comprise more, less, or functionallyequivalent modules and still be within the scope of present embodiments.For example, as previously discussed, the functions of the variousmodules may be combined or divided differently.

FIG. 3 depicts another transmitting radio frequency unit 300 in someembodiments. The transmitting radio frequency unit 300 may comprisemixer modules 302 and 316, filter modules 304, 308, 318, and 322,oscillator modules 306 and 320, a phase adjuster 310, an automatic gaincontrol (AGC) module 312, amplification/attenuation modules 314 and 324,waveguide filter 326, and waveguide 328. The transmitting radiofrequency unit 302 may further comprise a signal quality module that maycontrol the phase adjuster 310 and/or the AGC module 312.

In various embodiments, the transmitting radio frequency unit 300 is apart of the ODU 110. Although the transmitting radio frequency unit 300is depicted with a box around the circuitry of the transmitting radiofrequency unit 300, the transmitting radio frequency unit 300 may not beseparated from the attenuator 204, filter modules 206 and 208, gainmodule 210, and/or the controller 212.

The mixer module 312, filter module 314, and the oscillator module 316may represent an upconverter configured to upconvert the signal 216received from the gain module 210 (see FIG. 2) to an intermediatefrequency signal. Similarly, the mixer module 326, filter module 328,and oscillator module 330 also may represent an upconverter configuredto further upconvert the signal to an RF signal. Those skilled in theart will appreciate that there may be any number of upconvertersconfigured to upconvert the signals within the transmitting radiofrequency unit 302.

The mixer modules 302 and 316 may comprise mixers configured to mix thesignal(s) provided by the modem with one or more other signals. Themixer modules 302 and 316 may comprise many different types of mixerswith many different electrical properties. In one example, the mixer 302mixes the signal 216 received from the gain module 210 with the filteredoscillating signal from the filter module 304 and the oscillator module306. In another example, the mixer module 316 mixes a signal receivedfrom the amplifier/attenuator module 314 with the filtered oscillatingsignal from the filter module 318 and the oscillator module 320.

Those skilled in the art will appreciate that each of the mixers 302 and316 may be the same as one or more other mixer modules. For example,mixer modules 302 and 316 may both be mixers sharing the same electricalproperties or, alternately, the mixer 302 and 316 may be another kind ofmixer and/or with different electrical properties. Each mixer modules302 and 316 may include one or more components. For example, the mixermodule 302 may comprise one or more mixers.

The filter modules 304, 308, 318, and 322 may comprise filtersconfigured to filter the signal. The filter modules 304, 308, 318, and322 may comprise many different types of filters (e.g., bandpass filter,low pass filter, high pass filter, or the like) with many differentelectrical properties. In one example, the filter module 304 may be aband pass filter configured to filter the oscillation signal (orcomponents of the signal) provided from the oscillator module 306.Similarly, filter modules 304, 308, 318, and 322 may filter signals (orcomponents of the signals) from the oscillator module 306, theoscillator module 320, the mixer module 302, or the mixer module 316,respectively.

Those skilled in the art will appreciate that each of the filter modules304, 308, 318, and 322 may be the same as one or more other filtermodules. For example, filters modules 304 and 308 may both be filterssharing the same electrical properties while filter module 318 may beanother kind of filter. In another example, filters module 304 and 308may both be filters of a similar type but have different electricalproperties.

Each filter modules 304, 308, 318, and 322 may include one or morecomponents. For example, the filter modules 304 may comprise one or morefilters.

The oscillator modules 306 and 320 may comprise oscillators configuredto provide an oscillating signal that may be used to upconvert thesignal. The oscillator modules 306 and 320 may comprise any kind ofoscillator with any different electrical properties. In one example, theoscillator module 306 provides an oscillating signal to the filtermodule 304. The oscillator module 320 may provide an oscillating signalto the filter module 318.

The oscillator modules 306 and 320, either individually or together, maybe local or remote. In one example, the oscillating module 306 and/orthe oscillating module 320 may be remotely located and configured toprovide an oscillating signal to one or more transmitting radiofrequency units. In some embodiments, a single oscillating module mayprovide an oscillating signal to both the mixer module 302 and 316,respectively (e.g., optionally via a filter). In one example, theoscillator signal from the oscillator module may be altered (e.g.,oscillation increased or decreased) and provided to a different part ofthe circuit.

Those skilled in the art will appreciate that each of the oscillatormodules 306 and 320 may be the same as each other. For example,oscillator modules 306 and 320 may both be oscillators sharing the sameelectrical properties or, alternately, the oscillator modules 306 and320 may be another kind of oscillator and/or with different electricalproperties. Each oscillator modules 306 and 320 may include one or morecomponents. For example, the oscillator module 306 may comprise one ormore oscillators.

In various embodiments, the transmitting radio frequency unit 300includes a signal quality module. The signal quality module may beconfigured to generate a phase control signal to control the phase of aprocessed signal. In one example, the signal quality module receives theupconverted RF signal from the amplifier/attenuator module 324 and mixesthe amplified or attenuated signal with the filtered oscillator signalor the upconverted signal from the second upconverter. The signalquality module may filter the signal and compare the filtered, mixedsignal with a predetermined phase value to generate a phase controlsignal based on the comparison.

The phase adjuster 310 may comprise a variable phase control circuitconfigured to increase or decrease the phase of the signal to betransmitted. The phase adjuster 310 may comprise any different type ofphase adjuster or phase shifter with different electrical properties. Inone example, the phase adjuster 310 increases or decreases the phase ofthe signal received from the filter module 308. The phase adjuster 310may adjust the phase of the signal based on the phase control signalfrom the signal quality module.

The phase adjuster 310 may include one or more components. For example,the phase adjuster 310 may comprise one or more phase control elements.

The AGC module 312 may comprise an automatic gain control (AGC) circuitconfigured to increase or decrease the gain of the signal received fromthe phase adjuster 310. The AGC module 312 may comprise many differenttypes of AGCs with many different electrical properties. In one example,the AGC module 312 increases or decreases the gain of the signalreceived from the phase adjuster 310. The AGC module 312 may adjust thegain of the signal based on the gain control signal.

The AGC module 312 may include one or more components. For example, theAGC module 312 may comprise one or more AGCs.

In various embodiments, in order to adjust the phase of the signal orthe amplitude of the signal, the signal quality module may providecontrol signals to adjust the filtered signal from the filter module 308to achieve the desired adjustment. For example, in order to adjust thephase or amplitude of the signal, the signal quality module may comparethe phase and amplitude of the signal to be provided to the waveguidefilter 326 and/or the waveguide 328 based on a predetermined phase valueand/or a predetermined amplitude value. Based on the comparison, thesignal quality module may generate phase and gain control signals toachieve the desired adjustment.

In some embodiments, the predetermined phase value and amplitude valuemay be the same or substantially similar as the phase and amplitude ofthe wireless signals outputted by one or more other transmitting radiofrequency units. In one example, the phase and the amplitude of one ormore transmitting radio frequency unit may be synchronized.

The amplification/attenuation modules 314 and 324 may comprise anamplifier and/or an attenuator configured to amplify and/or attenuate asignal. The amplification/attenuator modules 314 and 324 may be any kindof amplifiers and/or attenuators. Further, the amplification/attenuatormodules 314 and 324 may each comprise amplifiers and/or attenuators withany kind of electrical properties.

In some embodiments, the amplifier/attenuator module 314 receives asignal from the AGC module 312. The amplifier/attenuator module 314 mayamplify or attenuate the signal. Further, the amplifier/attenuatormodule 324 may attenuate the signal (or components of the signal) afterthe signal has been upconverted by the mixer module 316, the filtermodule 318, and the oscillator module 320. The amplifier/attenuatormodule 324 may then provide the signal to the signal quality moduleand/or the waveguide filter 326.

Those skilled in the art will appreciate that each of theamplifier/attenuator modules 314 and 324 may be the same as one or moreother amplifier/attenuator modules. For example, amplifier/attenuatormodules 314 and 324 may both be amplifiers sharing the same electricalproperties. In another example, amplifier/attenuator modules 314 and 324may both be amplifiers but have different electrical properties.

The transmitting radio frequency unit 300 may comprise the waveguidefilter 326 and the waveguide 328. The waveguide filter 326 may be anyfilter coupled to the waveguide 328 and configured to filter theelectromagnetic waves (e.g., remove noise). The waveguide 328 mayprovide the signal to an antenna via a diplexer. The diplexer mayprovide the signal to the antenna. The waveguide 328 may be anywaveguide kind or type of waveguide. For example, the waveguide 328 maybe hollow or dielectric. In some embodiments, the waveguide 328comprises a rectangular to circular waveguide.

FIG. 4 is a block diagram of a portion of an indoor unit (IDU) 108 insome embodiments. The portion of the IDU 108 may comprise similarcomponents as the portion of the ODU 110. For example, the portion ofthe ODU 108 comprises an attenuator module 404, filter modules 406 and408, and a gain module 410. The IDU 108 may optionally include acontroller 412 and a sensor 414. The attenuator module 404 may becoupled with a cable 202 that propagates signals between the ODU 110 andthe IDU 108. Filter module 406 may filter attenuated non-reflectedsignals received from the ODU 110. The filter module 408 may filtersignals received from other components of the IDU 108 via the line 418before providing the signal to the attenuator module 404 for attenuationand transmission to the ODU 110 over the cable 202. The gain module 410may adjust the gain of a signal from the filter module 406 beforeproviding the signal to the rest of the IDU 108 components via line 416.

In various embodiments, the IDU 108 is a transceiver module configuredto receive signals from a digital device, processor, or memory to beprocessed and provided to the ODU 110 to ultimately be transmitted by anantenna (i.e., transmission signals). The IDU 108 may also receive andprocess signals over cable 202 from the ODU 110 (e.g., signals receivedfrom the antenna) to provide to the digital device, processor or memory(i.e., receive signals). The signal may ultimately be demodulated andprovided to a digital device or the like.

The attenuator module 404 may comprise an attenuator configured toattenuate a signal. In various embodiments, the attenuator module 404attenuates signals from the ODU 110 received over the cable 202. Theattenuator module 404 may also attenuate signals received from a digitaldevice and provided to the ODU 110 over the cable 202.

In one example, the attenuator module 404 may attenuate a receive signalfrom the ODU 110. The receive signal may be provided by the ODU 110 froma microwave or any RF antenna. The attenuator module 404 may attenuatethe receive signal before providing the receive signal to the diplexer,filter modules, or any other component. A portion of the receive signalmay be reflected by one or more components of the IDU 108 (e.g., thediplexer or the filter modules 406 and/or 408). The reflected signal mayagain be attenuated by the attenuator module 404 before the reflectedsignal is transmitted back to the ODU 110 over the cable 202. If aportion of the reflected signal is reflected by the ODU 110 back to theIDU 108, the attenuator module 404 may attenuate the signal a third timewhile any new signals provided by the ODU 110 to be received may beattenuated only once. As a result of the multiple attenuations incomparison to the receive signal, the reflected portions of the signalslose strength and noise is reduced. The attenuator module 204 may be anykind of attenuator.

In some embodiments, the ODU 110 comprises a diplexer coupled to filtermodules 406 and 408. The diplexer may provide signals at a firstfrequency and/or from the attenuator module 404 to the filter module406. The diplexer may also provide signals at a second frequency and/orfrom the filter module 408 to the attenuator module 404. Those skilledin the art will appreciate that any splitter or switch may be used inplace of or in addition to the diplexer.

The filter modules 406 and 408 may comprise filters configured to filtersignals from the attenuator module 404 or from other circuitry of theIDU 108. The filter modules 406 and 408 may comprise many differenttypes of filters (e.g., bandpass filter, low pass filter, high passfilter, or the like) with many different electrical properties. In oneexample, the filter module 406 may be a band pass filter configured tofilter the attenuated receive signal. The filter module 408 may also bea bandpass filter configured to filter a signal from other components ofthe IDU 108 (e.g., from a modem).

Those skilled in the art will appreciate that each of the filter modules406 and 408 may be the same as one or more other filter modules. Forexample, filters module 406 may kind of filter and the other filter 408may be another kind of filter. In another example, filters module 406and 408 may both be filters of a similar type but have differentelectrical properties. Each filter modules 406 and 408 may include oneor more components. For example, the filter modules 406 may comprise oneor more filters.

The gain module 410 may comprise one or more amplifiers configured toamplify the signal received from the filter module 406. In variousembodiments, the gain module 410 may be configured to adjust the gain ofthe signal lost in attenuation. The signal from the filter module 406may then be at a proper level for other components of the IDU 108 (e.g.,an I/Q processor, modem, or the like). The gain module 210 may includeany kind of amplifiers and/or attenuators.

In various embodiments, the IDU 108 may comprise a controller 412configured to calibrate and/or control the attenuator module 404. Insome embodiments, similar to the controller 212, the controller 412 maybe configured to calibrate and/or control the gain module 410. Thecontroller 412 may be configured to detect a desired power level of thereceive signal and correlate the desired power to the desired level ofattenuation. For example, if the power level of the receive signal istoo high, then attenuation may need to increase to ensure that thereflected signals are sufficiently attenuated to reduce or eliminate theimpact of the triple transit effect on the desired receive signal.Alternately, if the power level of the receive signal is too low, thenthe attenuation may need to decrease to ensure that a sufficient powerlevel of the receive signal is provided to the rest of the IDU 108(e.g., for transmission over the antenna).

In one example, the controller 412 receives a sample or other signalrelated to the receive signal. In some embodiments, a sensor 414provides the sample or other signal to the controller 412. The sensor414 may be any kind of sensor (e.g., a sampler or the like). Thecontroller may compare the sensor signal from the sensor 414 to one ormore attenuator thresholds (e.g., one or more predetermined values).Based on the comparison, the controller 212 may generate an attenuatorcontrol signal to control the attenuator module 404.

The sensor 414 is depicted in FIG. 4 as being between the filter module406 and the gain module 410. Those skilled in the art will appreciatethat the sensor 214 may be located between the attenuator module 404 andthe filter module 406 or any other position.

In various embodiments, the controller 412 may be configured todetermine an expected strength (e.g., power level) of the sensor signal.If the power level of the sensor signal is within an expected range ofone or more attenuation thresholds (e.g., +/−5% of a single attenuationthreshold), the controller 412 may control the attenuator module 404 tomaintain existing attenuation. In some embodiments, when the desiredattenuation is reached, the controller 412 may not generate anattenuation control signal. If the sensor signal is below a lowattenuation threshold, the controller 412 may control the attenuatormodule 404 to reduce attenuation. If the sensor signal is above a highattenuation threshold, the controller may control the attenuator module404 to increase attenuation.

The controller 412 may also be configured to control the gain module410. In some embodiments, the controller compares the detected power ofthe receive signal (e.g., the sensor signal) to one or more gainthresholds. If the power level of the sensor signal is within anexpected range of one or more gain thresholds (e.g., +/−7% of a singlegain threshold), the controller 412 may control the gain module 410 tomaintain existing attenuation. In some embodiments, when the desiredattenuation is reached, the controller 412 may not generate a gaincontrol signal. If the sensor signal is below a low gain threshold, thecontroller 412 may control the gain module 410 to reduce attenuation. Ifthe sensor signal is above a high gain threshold, the controller maycontrol the gain module 210 to increase attenuation.

Lines 416 and 418 may be a conductive path (e.g., wire or trace) thatprovides signals to or from other components of the IDU 108.

In various embodiments, signals received from a modem via the line 418may be filtered by the filter module 408 and provided directly over thecable 402 without passing through the attenuator module 404. In oneexample, the ODU 110 includes an attenuator that may attenuate thesignal from the filter module 408 (see FIG. 2). In some embodiments, asignal from the modem may be filtered by the filter module 408 and besubsequently attenuated by the attenuator module 404 before propagatingthrough the cable 202. The ODU 110 may receive the signal via the cable202 and subsequently attenuate the signal.

In various embodiments, the IDU 108 may comprise attenuator 404, the ODU110 may comprise attenuator 204 (see FIG. 2), or both the IDU 108 andthe ODU 110 may comprise attenuators 404 and 204, respectively. Thoseskilled in the art will appreciate that if there is one attenuator 404or 204, reflected signals may be attenuated at least three separatetimes while the desired signal may be attenuated only once. If both theIDU 108 and the ODU 110 include attenuators, the reflected signal may beattenuated six times while the desired signal may be attenuated twice.

If both the IDU 108 and the ODU 110 include attenuators 204 and 404,respectively, a single controller (e.g., 214 or 414) may be configuredto control both attenuators 204 and 404. For example, the controller 214may detect the power of the signal to be provided to the modem andgenerate an attenuation control signal and/or a gain control signal. Theattenuation control signal may control the attenuator 204. Further, theattenuation control signal or a signal based on the attenuator controlsignal may be sent to the other transceiver unit (e.g., the ODU 110) tocontrol or assist in controlling the attenuator 404. Similarly, thecontroller 214 may generate a gain control signal to control the gainmodule 210 as well as the gain module 410. Alternately, the controller414 may be configured to control both the attenuator 404 and 204 as wellas gain modules 410 and 210.

Those skilled in the art will appreciate that if both the IDU 108 andthe ODU 110 include an attenuator module, the controllers 214 and/or 214may be calibrated or configured to take into account the multipleattenuators.

Those skilled in the art will appreciate that a short cable 202 (e.g.,the cable 202 is less than 75 feet) or a long cable 202 (the cable 202is greater than 500 feet) may reduce the triple transit effect. Forexample, the loss related to the length of cable 202 may result inreflected signals being naturally attenuated. Shorter cables 202 may notsignificantly attenuate the desired signal (e.g., the transmissionsignal or the receive signal). When the cable 202 length, however, isbetween the short cable length and the long cable length, additionalprecautions against the triple transit effect may be required.

In some embodiments, the attenuation by the attenuator 204 and/orattenuator 404 may be configured or calibrated so that the effect on thesignal is similar to the effect of a long cable 202 (e.g., a cable ofover 500 feet). For example, one or more of the attenuation thresholdsof the controller 214 and/or controller 414 may be based on the lossassociated with cable length in order to change attenuation as if thecable 202 was the desired length or the desired loss was attained.Similarly, one or more of the gain thresholds of the controller 214and/or controller 414 may be based on the loss associated with cablelength in order to adjust the gain as if the cable 202 was a longerlength.

FIG. 5 is a flow diagram for a method of reducing noise between twotransceiver units in some embodiments. In step 502, the attenuatormodule 204 of the ODU 110 may receive a transmission signal from the IDU108 over a coaxial cable 202. The transmission signal may containinformation to be transmitted over an antenna. In step 504, theattenuator module 204 attenuates the transmission signal.

In step 506, the attenuator module 204 may receive a reflection signalfrom a reflected portion of the transmission signal. In variousembodiments, any portion of the transmission signal from the IDU 108 maybe reflected by one or more components of the ODU 110. For example, aportion of the transmission signal may be reflected by the diplexerand/or filter modules 206 and 208.

In step 508, the attenuator module 204 may attenuate the reflectionsignal. Those skilled in the art will appreciate that the energy of thereflection signal may have been attenuated at least twice. For example,the energy of the reflection signal is attenuated as the signal passesfrom the IDU 108 to the ODU 110. The energy of the reflection signal isagain attenuated after all or a portion of the reflection signal isreflected from the ODU 110 back to the IDU 108.

Upon reaching the IDU 108, one or more components of the IDU 108 mayreflect all or a portion of the reflection signal back to the ODU 110.The reflected portion of the reflection signal may be passed back to theODU 110 while new transmission signals are being provided to the ODU110. The attenuator 204 of the ODU 110 may attenuate both the newtransmission signals and the reflected portion of the reflection signal.Those skilled in the art will appreciate that, at this point, thereflected portion of the reflection signal may be attenuated at leastthree separate times. As a result, the reflected portion of thereflection signal may include significantly less energy than the desirednew transmission signals thereby reducing noise caused by thereflections.

In step 510, the filter module 206 filters a portion of the attenuatedtransmission signal. In some embodiments, the filter module 206 filtersthe portion of the transmission signal that was not reflected by othercomponents of the ODU 110. The filter module 206 may be a bandpassfilter.

In step 512, the gain module 210 adjusts the gain of the filteredportion of the attenuated transmission signal. The gain module 210 mayincrease the gain of the transmission signal to prepare the signal to bereceived by other components of the ODU 110. Those skilled in the artwill appreciate that the attenuator module 204 may be configured toattenuate the transmission signal such that there is insufficient energyin the signal to be effectively processed by one or more of the othercomponents of the ODU 110. Alternately, one or more increasinglyexpensive components may be required to process the lower energy signal.In various embodiments, the gain module 210 may adjust the gain of thesignal to limit or eliminate the impact of the attenuator module 204.

In various embodiments, the attenuator module 204 and/or the gain module210 may be controlled, at least in part, by the controller 212. Forexample, a sensor 214 may generate a sensor signal based, at least inpart, on the transmission signal. The controller 212 may compare thesensor signal to a predetermined attribution threshold and/or apredetermined gain threshold. In various embodiments, the controller 212stores a desired range of one or more attributes of the sensor signal.The attributes may include, but are not limited to, power, energy,phase, current, voltage, or any other attribute. The controller 212 maydetermine if the sensor signal is associated with the desired range bycomparing one or more attributes of the sensor signal to the attenuationthreshold and/or the gain threshold. If the sensor signal is below adesired attenuation range, the controller 212 may generate an attenuatorcontrol signal to control the attenuator module 204 to decreaseattenuation. If the sensor signal is above the desired attenuationrange, the controller 212 may generate an attenuator control signal tocontrol the attenuator module 204 to increase attenuation. If the sensorsignal is within the desired attenuation range, the controller 212 maycontrol the attenuator module 204 to continue existing attenuation ormay not generate any signal thereby allowing the attenuator module 204to function with an existing configuration.

Similarly, if the sensor signal is below a desired gain range, thecontroller 212 may generate a gain control signal to control the gainmodule 210 to increase gain. If the sensor signal is above the desiredgain range, the controller 212 may generate a gain control signal tocontrol the gain module 210 to decrease gain. If the sensor signal iswithin the desired gain range, the control module 212 may control thegain module 210 to continue existing gain or may not generate any signalthereby allowing the gain module 210 to function with an existingconfiguration.

In step 514, an upconverter may upconvert the gain adjusted, filteredportion of the transmission signal to an intermediate frequency. In step516, the intermediate frequency signal (e.g., the upconverted, gainadjusted, filtered portion of the transmission signal) is subsequentlyprocessed to generate a transmitter signal. In one example, theintermediate frequency signal is filtered by filter module 308, phaseadjusted by phase adjuster module 310, gain adjusted by AGC module 312,and/or amplified by amplifier/attenuator module 314. Those skilled inthe art will appreciate that the intermediate frequency signal may beprocessed in any number of ways. For example, the intermediate frequencysignal may be filtered but not phase or gain adjusted.

In step 518, a second upconverter may upconvert the transmitter signalto a frequency that may be transmitted by an antenna. For example, thesecond upconverter may generate a higher frequency transmitter signal.In step 520, a waveguide filter 326 may filter the upconverted signalfrom the second upconverter. In step 522, a waveguide 328 may providethe higher frequency signal to an antenna. In step 524, the antenna maytransmit the higher frequency signal.

The IDU 108 may operate in a similar manner as that discussed withrespect to FIG. 5. For example, the attenuator module 404 of the IDU 108may receive a receive signal from the ODU 110 over a coaxial cable 202.The receive signal may contain information to be received by a digitaldevice, processor, or memory (e.g., over line 416). In one example, amodem may demodulate the receive signal to provide the information tothe digital device, processor, or memory. The attenuator module 404 mayattenuate the receive signal.

The attenuator module 404 may receive a reflection signal from areflected portion of the receive signal. In various embodiments, anyportion of the receive signal from the ODU 110 may be reflected by oneor more components of the IDU 108. For example, a portion of the receivesignal may be reflected by the diplexer and/or filter modules 406 and408.

The attenuator module 404 may attenuate the reflection signal. Theenergy of the reflection signal is again attenuated after the reflectionsignal is reflected from the IDU 108 back to the ODU 110.

Upon reaching the ODU 110, one or more components of the ODU 110 mayreflect all or a portion of the reflection signal back to the IDU 108.The reflected portion of the reflection signal may be propagating backto the IDU 108 while new receive signals are being provided to the IDU108. The attenuator 404 of the IDU 108 may attenuate both the newreceive signals and the reflected portion of the reflection signal.Those skilled in the art will appreciate that, at this point, thereflected portion of the reflection signal may be attenuated at leastthree separate times. As a result, the reflected portion of thereflection signal may include significantly less energy than the desirednew receive signals thereby reducing noise caused by the reflections.

The filter module 406 may filter a portion of the attenuated receivesignal. In some embodiments, the filter module 406 filters the portionof the receive signal that was not reflected by other components of theIDU 108. The filter module 406 may be a bandpass filter.

The gain module 410 adjusts the gain of the filtered portion of thereceive signal. The gain module 410 may increase the gain of the receivesignal to prepare the signal to be received by other components of theIDU 108. Those skilled in the art will appreciate that the attenuatormodule 404 may be configured to attenuate the receive signal such thatthere is insufficient energy in the signal to be effectively processedby one or more of the other components of the IDU 108. Alternately, oneor more increasingly expensive components may be required to process thelower energy signal. In various embodiments, the gain module 410 mayadjust the gain of the signal to limit or eliminate the impact of theattenuator module 404.

In various embodiments, the attenuator module 404 and/or the gain module410 may be controlled, at least in part, by the controller 412. Forexample, a sensor 414 may generate a sensor signal based, at least inpart, on the receive signal. The controller 212 may compare the sensorsignal to a predetermined attribution threshold and/or a predeterminedgain threshold. In various embodiments, the controller 412 stores adesired range of one or more attributes of the sensor signal. Theattributes may include, but are not limited to, power, energy, phase,voltage, current, or any other attribute. The controller 412 maydetermine if the sensor signal is associated with the desired range bycomparing one or more attributes of the sensor signal to the attenuationthreshold and/or the gain threshold. If the sensor signal is below adesired attenuation range, the controller 212 may generate an attenuatorcontrol signal to control the attenuator module 404 to decreaseattenuation. If the sensor signal is above the desired attenuationrange, the controller 412 may generate an attenuator control signal tocontrol the attenuator module 404 to increase attenuation. If the sensorsignal is within the desired attenuation range, the controller 412 maycontrol the attenuator module 404 to continue existing attenuation ormay not generate any signal thereby allowing the attenuator module 404to function with an existing configuration.

Similarly, if the sensor signal is below a desired gain range, thecontroller 412 may generate a gain control signal to control the gainmodule 410 to increase gain. If the sensor signal is above the desiredgain range, the controller 412 may generate a gain control signal tocontrol the gain module 410 to decrease gain. If the sensor signal iswithin the desired gain range, the control module 412 may control thegain module 410 to continue existing gain or may not generate any signalthereby allowing the gain module 410 to function with an existingconfiguration.

After adjusting the gain of the signal, the signal may be provided to amodem or other processing component over line 416.

FIG. 6 is a flow diagram for configuring an attenuator module 204 and again module 210 to reduce noise in transceiver communications in someembodiments. In various embodiments, the controller 212 may configurethe attenuator module 204 (e.g., to obtain the desired attenuation)before configuring the gain module 210 (e.g., to obtain the desiredgain). In step 602, the sensor 214 may generate a sensor signal based onone or more attributes of a first transmission signal.

In step 604, the controller 212 may compare one or more attributes ofthe sensor signal to one or more attribution thresholds. In step 606,the controller 212 may control the attenuator module 204 based on thecomparison. For example, the controller 212 may configure the attenuatormodule 204 to increase or decrease attenuation based on the comparison.Subsequent signals received by the ODU 110 may then be attenuated basedon the newly configured attenuator module 204.

In step 608, the sensor 214 may generate a sensor signal based on one ormore attributes of a second transmission signal. In various embodiments,the IDU 108 may provide new transmission signals to the ODU 110 that areattenuated by the attenuator module 204.

In step 610, the controller 212 may compare one or more attributes ofthe sensor signal to one or more attribution thresholds and/or one ormore gain thresholds. In some embodiments, the controller 212 comparesone set of attributions to the attribution threshold(s) and a differentset of attributes to the gain threshold(s). In various embodiments, thetwo sets of attributes share one or more attributes. In otherembodiments, the two sets do not share any attributes.

In step 612, the controller 212 may control the gain module 210 based onthe comparison. For example, the controller 212 may configure the gainmodule 210 to increase or decrease gain based on the comparison.

In optional step 614, the controller 212 may control the attenuatormodule 204 based on the comparison of the one or more attributes of thesecond transmission signal to the attenuation threshold(s).Subsequently, the controller 212 may continue to compare sensor signalsbased on new transmission signals to the threshold(s) to adjustattenuation and/or gain accordingly. In various embodiments, theattenuation threshold(s) and the gain threshold(s) are the samethreshold(s).

In some embodiments, the controller 412 of the IDU 108 may calibrateand/or control the attenuator module 404 and/or the gain module 410 in asimilar manner as discussed regarding FIG. 6. For example, thecontroller 412 may configure the attenuator module 404 (e.g., to obtainthe desired attenuation) before configuring the gain module 410 (e.g.,to obtain the desired gain). Similar to the ODU 110, the sensor 414 ofthe IDU 108 may generate a sensor signal based on one or more attributesof a first receive signal. The controller 412 may compare one or moreattributes of the sensor signal to one or more attribution thresholds.The controller 212 may control the attenuator module 404 based on thecomparison. Subsequent signals received by the IDU 108 may then beattenuated based on the newly configured attenuator module 404.

The sensor 214 may generate a sensor signal based on one or moreattributes of a second receive signal. The controller 412 may compareone or more attributes of the sensor signal to one or more attributionthresholds and/or one or more gain thresholds. The controller 412 maycontrol the gain module 410 based on the comparison. For example, thecontroller 412 may configure the gain module 410 to increase or decreasegain based on the comparison.

The controller 412 may control the attenuator module 404 based on thecomparison of the one or more attributes of the second receive signal tothe attenuation threshold(s). Subsequently, the controller 412 maycontinue to compare sensor signals based on new receive signals to thethreshold(s) to adjust attenuation and/or gain accordingly.

Various embodiments described herein separate transmit and receivesignals present on a single coaxial cable which couples two transceivers(e.g., an Indoor Unit (IDU)) with an Outdoor Unit (ODU)) of a microwaveradio system. In some embodiments, systems and methods may separatetransmit and receive signals when one or more of the signals comprise agroup of carriers (e.g., when one or more of the transmit and/or receivesignals are multi-carrier signals). In one example, the three signalsinclude a transmit signal (e.g., TX1), and two receive signals (e.g.,RX1 and RX2). In various embodiments, the signals may be separated sothat they can be processed with fidelity (e.g., within each of thesesignals, the multi-carriers may be separated a processed with fidelity).For example, in some embodiments described herein describe reduction orelimination of interference between signals on a cable between twotransceivers, reduction or elimination of thermal noise in “unused”carrier slots within the signal groups, and/or reduction or eliminationof triple transit echoes caused by reflection of the signals at each ofthe cable.

Some embodiments described herein allow a single transceiver module(e.g., the ODU) to be capable of emulating a collection of radios thatwould normally have been connected together with waveguide coupling andpresented to one antenna. Further, various embodiments described hereinallows for capacities above 1 GB to be carried in each direction on thecable between transceiver modules and allows selection of carrierswithin each of the signals to be turned on or off to adjust the capacitywhile meeting the critical TX emission mask specified by the FCC orETSI.

FIG. 7 is a block diagram of a portion of an outdoor unit (ODU) 110 insome embodiments. Various embodiments described herein allows of theprocessing of three signals (e.g., TX1, RX1, and RX2) which may transitover a single cable between transceiver units. Some embodiments describereduction or elimination of interference between signals on a cablebetween two transceivers, reduction or elimination of thermal noise in“unused” carrier slots within the signal groups, and/or reduction orelimination of triple transit echoes caused by reflection of the signalsat each of the cable.

In various embodiments, a portion of the ODU 110 comprises an attenuatormodule 704, splitter modules 706 and 708, amplifiers 710 and 712, gainmodule 714, filter module 716, and a controller 722 coupled to sensor720. The attenuator module 704 may be coupled with a cable 702 thatpasses signals between the ODU 110 and the IDU 108.

In various embodiments, the ODU 110 is a transceiver module configuredto receive signals from the IDU 108 to be processed and provided to anantenna for wireless transmission in a manner similar to the ODU 110 andODU 108 discussed with regard to FIG. 2. The ODU 110 may also receiveand process signals from the antenna to provide to the IDU 108 overcable 702. The signal may ultimately be demodulated and provided to adigital device or the like.

The attenuator module 704 may comprise an attenuator configured toattenuate a signal. In various embodiments, the attenuator module 704attenuates signals from the IDU 108 received over the cable 702. Theattenuator module 704 may also attenuate signals received from anantenna and provided to the IDU 108 over the cable 702. The attenuatormodule 704 may, in some embodiments, be voltage controlled or currentcontrolled. The attenuator module 704 may be similar to the attenuatormodule 204. As discussed herein, in various embodiments, an attenuatorat or near the interface between a transceiver unit and cable may allowthe use of fixed value elements and avoid or reduce the tuning process.

In one example, the attenuator module 704 may attenuate a multicarriertransmit signal from the IDU 108. The multicarrier transmit signal maybe provided by the IDU 108 to be processed and transmitted by amicrowave or any RF antenna. The attenuator module 704 may attenuate themulticarrier transmit signal before providing the multicarrier transmitsignal to the splitter module 706, or any other component. A portion ofthe transmission signal may be reflected by one or more components ofthe ODU 110 (e.g., the splitter module 706, splitter module 708,amplifiers 710 and 712, gain module 714, and/or filter module 716). Thereflected signal may again be attenuated by the attenuator module 704before the reflected signal is transmitted back to the IDU 108 over thecable 702. Those skilled in the art will appreciate that the unwantedportion of the signal has been attenuated twice in this example. If aportion of the reflected signal is reflected by the IDU 108 back to theODU 110, the attenuator module 704 may attenuate the signal a third timewhile any new signals provided by the IDU 108 to be transmitted may beattenuated only once. As a result of the multiple attenuations incomparison to the transmission signal, the reflected portions of thesignals lose energy and noise is reduced. The attenuator module 704 maybe any kind of attenuator.

In some embodiments, the ODU 110 comprises splitter module 706 which iscoupled to the attenuator module 704, splitter module 708, and gainmodule 714. The splitter module 706 may provide signals from theattenuator module 704 (e.g., the multicarrier transmit signal) to thesplitter module 708 and the gain module 714. The splitter module 706 mayalso receive one or more receive signals from the splitter module 708and provide the signals to the attenuator module 704 and the gain module714. The splitter module 706 may be any kind of splitter module.

Splitter module 708 may be similar to the splitter module 706. Thesplitter module 708 may combine receive signals from the amplifiers 710and the amplifier 712, respectively. In various embodiments, the portsof the splitter module 708 coupled to the amplifier 710 and 712 mayprovide isolation to the receive signals. Those skilled in the art willappreciate that there may be any degree or amount of isolation provideby the ports. In various embodiments, the ports of the splitter module708 may provide 20 or 25 dB of isolation.

The amplifiers 710 and 712 may be configured to receive a first andsecond receive signals (e.g., from the antenna), respectively, andprovide the receive signals to the splitter module 708. In one example,each receive signal is initially received by the antenna as anorthogonally polarized signal. The first polarized signal and the secondpolarized signal may be filtered by waveguide filters to generate firstand second receive signals and/or be downconverted.

The first and second receive signals may be at different frequenciesfrom each other. In some embodiments, different receivers convert thetwo receive signals to different frequencies. Further, the first andsecond receive signals may be at a different frequency than themulticarrier transmit signal. In some examples, the first receive signalmay be at 126 MHz and the second receive signal may be at 500 MHz. Themulticarrier transmit signal may be at 311 MHz. Those skilled in the artwill appreciate that the multicarrier transmit signal, the first receivesignal, and the second receive signal may be at any frequencies. In someexamples, carrier groups of the multicarrier transmit signal may besingle, dual, triple, or quadruple carriers.

In various embodiments, all three signals maybe present and crossing thecable 702 at the same time. In some embodiments, the ODU 110 and/or theIDU 108 may each comprise an Nplexer configured to provide and transmitsignals at different frequencies across the cable 702.

The amplifiers 710 and 712 may amplify the first and second receivesignals. In some embodiments, the amplifiers 710 and 712 are unityamplifiers. Amplifiers 710 and 712 may be any kind of amplifiers.

The gain module 714 may comprise one or more amplifiers configured toamplify the signal received from the splitter module 706. In variousembodiments, the gain module 714 may be configured to adjust the gain ofthe signal lost in attenuation. The signal from the splitter module 706may then be at a proper level for other components of the ODU 110 (seeFIG. 3). The gain module 714 may include any kind of amplifiers and/orattenuators. The gain module 714 may, for example, be voltage controlledor current controlled.

In various embodiments, the ODU 110 may comprise a controller 722configured to calibrate and/or control the attenuator module 704. Insome embodiments, the controller 722 may be configured to calibrateand/or control the gain module 714. The controller 722 may be configuredto detect a desired power level of the transmission signal and correlatethe desired power to the desired level of attenuation. For example, ifthe power level of the transmission signal is too high, then attenuationmay need to increase to ensure that the reflected signals aresufficiently attenuated to reduce or eliminate the impact of the tripletransit effect on the desired multicarrier transmit signal. Alternately,if the power level of the multicarrier transmit signal is too low, thenthe attenuation may need to decrease to ensure that a sufficient powerlevel of the multicarrier transmit signal is provided to the rest of theODU 110 (e.g., for transmission over the antenna).

In one example, the controller 722 receives a sample or other signalrelated to the multicarrier transmit signal. A sensor 720 may providethe sample or other signal to the controller 722. The sensor 720 may beany kind of sensor (e.g., a sampler or the like). The controller 722 maycompare the sensor signal from the sensor 720 to one or more attenuatorthresholds (e.g., one or more predetermined values). Based on thecomparison, the controller 722 may generate an attenuator control signalto control the attenuator module 704.

The sensor 720 is depicted in FIG. 7 as being after the filter module716. Those skilled in the art will appreciate that the sensor 714 may belocated between the attenuator module 704 and the splitter module 706,between the splitter module 706 and the gain module 714, or any otherposition.

In various embodiments, the controller 722 may be configured todetermine an expected strength (e.g., power level) of the sensor signal.If the power level of the sensor signal is within an expected range ofone or more attenuation thresholds (e.g., +/−5% of a single attenuationthreshold), the controller 722 may control the attenuator module 704 tomaintain existing attenuation. In some embodiments, when the desiredattenuation is reached, the controller 722 may not generate anattenuation control signal. If the sensor signal is below a lowattenuation threshold, the controller 722 may control the attenuatormodule 704 to reduce attenuation. If the sensor signal is above a highattenuation threshold, the controller may control the attenuator module704 to increase attenuation.

The controller 722 may also be configured to control the gain module714. In some embodiments, the controller compares the detected power ofthe transmission signal (e.g., the sensor signal) to one or more gainthresholds. If the power level of the sensor signal is within anexpected range of one or more gain thresholds (e.g., +/−7% of a singlegain threshold), the controller 722 may control the gain module 714 tomaintain existing gain adjustment. In some embodiments, when the desiredgain is detected, the controller 714 may not generate a gain controlsignal. If the sensor signal is below a low gain threshold, thecontroller 722 may control the gain module 714 to increase gain. If thesensor signal is above a high gain threshold, the controller may controlthe gain module 714 to decrease gain.

Filter module 716 may be configured to filter the multicarrier transmitsignal. In some embodiments, the filter module 716 blocks receivesignals while allowing the multicarrier transmit signal to pass. Invarious embodiments, filter module 716 allows for a selection ofcarriers within a multi-carrier signal group to be on or off whilemeeting the stringent FCC and ETSI emission masks.

In various embodiments, the filter module 716 comprises a group offilters (e.g., a plurality) that can be enabled or disabled. In someembodiments, each filter of the group of filters is configured to filtera frequency bandwidth around a center frequency. In one example, eachfilter is a bandpass filter. The filter module 716 may comprise manydifferent types of filters (e.g., bandpass filter, low pass filter, highpass filter, or the like) with many different electrical properties.

As a result of enabling or disabling the filters, select signals can beprocessed while removing noise generated in unused channels. In someembodiments, insertion loss associated with providing the multicarriertransmit signal to the coaxial cable 702 causes thermal noise which maybe blocked and/or reduced by disabling filters for unused channels. Thesignals of the multicarrier transmit signal may be filtered and providedto other components of the ODU 110 (e.g., a transmitter, upconverter,power amplifier, and/or the like).

In various embodiments, the filter module 716 provides passage of the“wanted” carriers within the multicarrier transmit signal TX1 byenabling or disabling filters for signals that are present in themulticarrier transmit signal TX1. The filter module 716 may also rejectunwanted noise when carriers are not present in various “slots” bydisabling the corresponding filter. Some embodiments appear as thoughthey are a combination of several trunking radios that separately meetthe required FCC and ETSI emission masks. The filter module 716 mayreject receive signals RX1 and RX2 while maintaining the fidelity of themulticarrier transmit signal.

In various embodiments, the use of the attenuator module 704 may allowfor one or broader bandpass filters of the filter module 716. Withoutthe attenuator 704, increasing the bandwidth of the bandpass filters mayrequire extensive or significant tuning of the components of the ODU 110and/or the IDU 108. With the attenuator, significant tuning may not benecessary.

The cable 702 may include any number of cables. In one example, thecable 702 may comprise one or more coaxial cables. The coaxial cable(s)may be any kind of coaxial cable(s). Those skilled in the art willappreciate that any type of cable may be used.

Lines 718, 724, and 726 may be conductive paths (e.g., wires or traces)that provide signals to or from other components of the ODU 110. Invarious embodiments, signals received from an antenna via the lines 724and 726 may be received by amplifiers 710 and 712, respectively, andsubsequently combined by the splitter module 708.

In various embodiments, the ODU 110 may not include an attenuator modulebut the IDU 108 may include an attenuator module (see FIG. 4). In someembodiments, both the ODU 110 and the IDU 108 include an attenuator.

In one example, the ODU 110 receives the first and second receivesignals RX1 and RX2 from an antenna. For example, the first and secondreceive signals may be received by the antenna as orthogonally polarizedsignals. The polarized signals may be converted into electrical signalsand/or down-converted to IF frequencies. In some embodiments, one orboth receive signals may be converted to different frequencies. Forexample, the first receive signal may be at 126 MHz while the secondreceive signal may be at 500 MHz. Those skilled in the art willappreciate that the two receive signals may be at any frequency.

The first amplifier 710 may receive the first receive signal and thesecond amplifier 712 may receive the second receive signal. The firstand second amplifiers 710 and 712 may be any kind of amplifierconfigured to amplify the first and second receive signals,respectively. Those skilled in the art will appreciate that theamplifiers 710 and 712 may not amplify the voltage of the receivesignals (e.g., the amplifiers 710 and 712 are unity amplifiers).

The splitter module 708 combines the first and second receive signals.In various embodiments, the splitter module 708 receives the signalsover ports that provide isolation to the receive signals.

The splitter module 706 receives the first receive signal from thesplitter module 708 and passes a reduced version of the first receivesignal to the gain module 714 due to the port isolation (e.g., 20 dB).The amplifier module 714 may amplify the reduced first receive signalbut the reduced first receive signal may be rejected (e.g., blocked orattenuated) by the filter module 716. Similarly, the splitter module 706passes a reduced version of the second receive signal to the amplifiermodule 714 due to the port isolation (e.g., 20 dB). The amplifier module714 may amplify the reduced second receive signal but the reduced secondreceive signal may be rejected (e.g., blocked or attenuated) by thefilter module 716.

The splitter module 706 may also provide the first and second receivesignals to the cable 702 via the attenuator module 704.

It will be appreciated that a “module” may comprise software, hardware,firmware, and/or circuitry. In one example one or more software programscomprising instructions capable of being executable by a processor mayperform one or more of the functions of the modules described herein. Inanother example, circuitry may perform the same or similar functions.Alternative embodiments may comprise more, less, or functionallyequivalent modules and still be within the scope of present embodiments.For example, as previously discussed, the functions of the variousmodules may be combined or divided differently.

FIG. 8 is a flow chart for processing receive signals and a transmitsignal in a transceiver unit in some embodiments. A transceiver modulemay be any transceiver. In one example, the transceiver unit is an ODU110, IDU 108, or a transceiver unit that comprises components thatperforms functions of all or part of the ODU 110 and all or part of theIDU 108.

In various embodiments, a transceiver, such as ODU 110, may be coupledto a second transceiver (e.g., IDU 108) over a cable (e.g., in a splitmount system as described herein). The ODU 110 may be configured toreceive transmit signals from the cable and provide the transmit signalsto the antenna while receive one or more receive signals and provide thereceive signals to the cable. The two receive signals and the transmitsignal may propagate across the cable at any time (e.g., simultaneouslyor near simultaneously). In some embodiments, the transmit signal may besplit by a splitter module. The first split transmit signal may befiltered and provided to the antenna while the second split transmitsignal may be blocked at the output of one or more amplifiers. Inaddition to blocking the transmit signal, the amplifiers may providereceive signals to a splitter module which may provide a first splitreceive signal to the cable while the second split receive signal may beblocked, rejected, or attenuated by the filter module.

In some embodiments, the IDU 110 may provide protection against tripletransit effects as discussed herein. For example, the IDU 110 mayoptionally comprise an attenuator module, sensor, and controller (e.g.,similar to the attenuator module 204, sensor 214, and controller 212).For example, the attenuator module may attenuate reflections caused bythe splitter module 706, the splitter module 708, the amplifier 710, theamplifier 712, the gain module 714 and/or the filter module 716 as wellas reflected signals received from the cable 702.

In step 802, the first and second amplifiers 710 and 712 amplify thefirst and second receive signals from an antenna. For example, the ODU110 may receive orthogonally polarized signals from the antenna. One ofthe two signals may be horizontally polarized and the other of the twosignals may be vertically polarized. The two signals may be provided towaveguide filters via waveguide(s) to be converted into the first andsecond receive signals. The receive signals may be downconverted bydownconverters and/or receivers. The receive signals may also be atdifferent frequencies (e.g., converted to different frequencies byreceivers). In one example, the first receive signal is 126 MHz whilethe second receive signal is at 500 MHz.

In step 804, the first and second amplified signals are combined withthe first splitter module 708. In various embodiments, ports of thefirst splitter module 708 provides isolation between the two amplifiedreceive signals. There may be any amount of isolation. In some examples,the signals may be isolated by 20 dB, 25 dB, or more.

In step 806, the splitter module 706 (e.g., second splitter module)splits the combined receive signal from the splitter module 708. In step808, the splitter module 706 provides one of the split signals to atransceiver module (e.g., IDU 108) via the cable 702. In someembodiments, the splitter module 706 provides one of the split signalsto the attenuator module 704 which may attenuate the signal before thesignal is provided to the cable 702. In some embodiments, an nplexerreceives the split signal from the attenuator module 704 or the splittermodule 706 to provide the split signal on the cable 702.

In step 810, the splitter module 706 provides the other split signal tothe filter module 716. In some embodiments, the splitter module 706provides the other split signal to the gain module 714 which mayincrease the gain of the signal before providing the signal to thefilter module 716.

In step 812, the filter module 716 blocks passage of the split receivesignal from the splitter module 706. In one example, the split receivesignal is at a different frequency than transmit signals. The filtermodule 716 may be configured to block passage of frequencies that arenot the frequency of the transmit signals.

In some embodiments, the filter module 716 comprises a plurality offilters where each of the filters is coupled to a separate switch. Theswitches may be controlled to couple or decouple paths to the pluralityof filters. In some embodiments, the switches may be controlled by oneor more carrier selection signals to enable or disable the filters bycoupling or decoupling the filters with a path to receive all or part ofthe transmit signal. The filter comprising a plurality of filters, eachof the filters coupled to a separate switch is further described herein.

In step 814, the splitter module 706 receives a transmit signal from atransceiver module (e.g., IDU 108) via cable 702. The transmit signalmay be a multicarrier transmit signal. In various embodiments, thetransmit signal is received from an attenuator module 704 which mayattenuate the transmit signal before providing the attenuated transmitsignal to the splitter module 706.

In step 816, the splitter module 706 splits the transmit signal receivedfrom the cable 702 (e.g., via an nplexer and/or attenuator module 704).In step 818, the splitter module 708 receives a first part of the splittransmit signal from the splitter module 706 and divides the splittransmit signal. The divided signal from the splitter module 706 isprovided to outputs of the amplifier 710 and amplifier 712,respectively, which block the transmit signal from further propagatingin step 820.

In step 822, the filter module 716 receives the second split transmitsignal from the splitter module 706 (e.g., via the gain module 714) andfilters the signal. In step 824, the filter module 716 provides thefiltered transmit signal to the antenna (e.g., via other components ofthe ODU 110 such as an upconverter, transmitter, power amplifier,waveguide filter, waveguide and/or the like).

In various embodiments, there may be one receive signal rather than two.For example, amplifier 710 may receive the only receive signal from theantenna and provide the signal to the splitter module 706 (e.g., the ODU110 may not include amplifier 712 or splitter module 708). In thisexample, the receive signal may be split by the splitter module 706. Asdiscussed herein, one part of the split receive signal may be blocked bythe filter module 716 while the other part of the split receive signalmay be provided to the attenuator module 704 and/or the cable 702 (e.g.,via an nplexer). Further, the splitter module 706 may receive a transmitsignal from the cable 702 (e.g., via the nplexer and/or attenuatormodule 704) and provide the first part of the transmit signal to theoutput of amplifier 710 which blocks the signal. The splitter module 706may also provide the second part of the transmit signal to the filtermodule 716 (e.g., via the gain module 714) to be filtered as discussedherein.

FIG. 9 is a flow chart for filtering signals from a multicarriertransmit signal in some embodiments. In various embodiments, amulticarrier transmit signal may be received over a cable from atransceiver unit such as IDU 108. The multicarrier transmit signal mayhave any number of signals, however, there may be a build-up of noise(e.g., thermal noise) caused by coaxial cable insertion loss associatedwith “unused” carrier slots.

In various embodiments, a filter module comprising a plurality offilters may filter different frequency ranges of the multicarriertransmit signal. Each of the filters may be coupled to a differentswitch which may be controlled by a carrier selection switch. As aresult, “unused” carrier slots may be blocked by an open switch therebyreducing or eliminating noise.

Those skilled in the art will appreciate that the filters may havedifferent frequency ranges (e.g., different center frequency, differentbandwidth, or both).

In step 902, the ODU 110 receives the carrier selection signal from amodulation device over the cable 702. The modulation device may be amodem. In some embodiments, a second transceiver unit, such as an IDU108, comprises the modem. The carrier selection signal may be receivedfrom any component. In some embodiments, the carrier selection signal ispart or all of the telemetry information received from the IDU 108. Thecarrier selection signal may be any number of signals.

In step 904, the carrier selection signals may enable or disable asubset of filters of filter module 716. In various embodiments, acarrier management module may receive the carrier selection signal(s)and control switches associated with different filters. In someembodiments, the carrier management module controls all switches of theplurality of switches of the filter module 716. Alternately, the carriermanagement module may control a subset of the plurality of switches(e.g., control the subset to the plurality of switches to open orclose).

In various embodiments, the modem, telemetry module, or multicarriertransmit selection module provides the carrier selection signal to theODU 110. The modem, telemetry module, or multicarrier transmit selectionmodule may identify the used or unused carriers of the multicarriertransmit selection module and may provide the carrier selection signalto control switches of the filter module 716 to block the unused carrierslots.

In step 906, the ODU 110 receives the multicarrier transmit signal frommodulation device over the cable 702. In various embodiments, themulticarrier transmit signal, the first and second receive signals, andthe carrier selection signal may propagate over the cable 702simultaneously. In one example, the multicarrier transmit signal, thefirst and second receive signals, and the carrier selection signal mayeach be of different frequencies. In some embodiments, the signals maybe provided over or received from the cable 702 by an nplexer of the IDU108. Similarly, the signals may be provided over or received from thecable 702 by an nplexer of the ODU 110.

The multicarrier transmit signal may optionally be attenuated by theoptional attenuator module 704. Further, the splitter module 706 maysplit the multicarrier transmit signal into two parts. The first splitof the multicarrier transmit signal may be provided to an output of anamplifier (e.g., amplifier 710 which may provide the splitter module 706a receive signal from an antenna). In some embodiments, the first splitof the multicarrier transmit signal is further divided by anothersplitter module 708 which provides each of the divided, split,multicarrier transmit signal to the outputs of amplifiers 710 and 712,respectively.

The splitter module 706 may provide the second part of the splitmulticarrier transmit signal to the filter module 716 (e.g., after thegain module 714 increases the gain of the second part of the splitmulticarrier transmit signal).

In step 908, the filter module 716 filters signals of the multicarriertransmit signal utilizing coupled filters of the filter module 716. Insome embodiments, the carrier selection signal enables or disablesfilters of the filter module 716 by controlling switches to each filter.The carrier selection signal may control the switches to couple filtersof the filter module 716 to allow for filtering of the used carriers ofthe multicarrier transmit signal. The carrier selection signal maycontrol the switches to decouple filters of the filter module 716 toblock unused carrier slots to block thermal energy caused by insertionover the cable 702 in step 910.

In step 912, the filter module 716 provides the multicarrier transmitsignal to the antenna. In one example, the filter module 716 providesthe filtered multicarrier transmit signal to a transmitter, upconverter,filter, power amplifier, waveguide filter, and/or waveguide before thesignal is provided to the antenna.

FIG. 10 is an exemplary FCC operation bandpass filter in someembodiments. The FCC operation bandpass filter may be any filter module.In one example, the FCC operation bandpass filter may be filter module716. In various embodiments, the configuration of filter module 716depicted in FIG. 10 meets FCC emission masks.

In the example depicted in FIG. 10, the FCC operation bandpass filterincludes a plurality of filters (e.g., a plurality of filter modules1002-1014). Although FIG. 10 is identified as an FCC operation bandpassfilter, each filter of the plurality of filters may be any kind offilter. In some embodiments, all filters of the FCC operation bandpassfilter are the same type of filter. In one example, each filter is abandpass filter with a different frequency range. In variousembodiments, each or some of the filters in the FCC operation bandpassfilter may be different a different type of filter from one or moreother filters types of the FCC operation bandpass filter. In variousembodiments, each of the plurality of filter modules 1002-1014 maycomprise any number of filters.

In the example depicted in FIG. 10, each of the plurality of filters ofthe FCC operation bandpass filter is a bandpass filter centered at 311MHz and has a different range. For example, filter module 1002 iscentered at 311 MHz and has a bandwidth of 5 MHz. Filter module 1004 hasa bandwidth of 10 MHz, filter module 1006 has a bandwidth of 20 MHz,filter module 1008 has a bandwidth of 30 MHz, filter module 1010 has abandwidth of 40 MHz, filter module 1012 has a bandwidth of 50 MHz, andfilter module 1014 has a bandwidth of 80 MHz. Those skilled in the artwill appreciate that there may be any number of filter modules in theFCC operation bandpass filter. Further, those skilled in the art willappreciate that the filters may be at different center frequenciesand/or different bandwidths.

The FCC operation bandpass filter may comprise a plurality of switchesS0-S6, each of the plurality of switches coupled to a filter module. Theplurality of switches may be controlled by the carrier selectionsignal(s) to engage or disengage (e.g., open or close the switches) toenable or disable one or more of the plurality of filter modules1002-1014. Any or all of the switches S0-S6 may be controlled by thecarrier selection signal.

In various embodiments, the FCC operation bandpass filter may receive amulticarrier transmit signal. The signal may be provided to each of theplurality of switches. If a switch is open, the signal is blocked frombeing received by related a filter module of the plurality of filtermodules. If a switch is closed, the multicarrier transmit signal isfiltered by the related filter module of the plurality of filtermodules. In this example, each filter module is a bandpass filterallowing a frequency range to pass through the filter while attenuatingother frequencies. As a result, used carriers pass through the FCCoperation bandpass filter to be combined by combiner 1016 while unusedcarriers of the multicarrier transmit signal are blocked (e.g.,attenuated by the coupled filter modules of the plurality of filtermodules).

The combiner 1016 provides the filtered multicarrier transmit signal toother components of the ODU 110 and/or an antenna. Those skilled in theart will appreciate that one or more of the filter module of the FCCoperation bandpass filter may be coupled to any number of switches orlogic circuitry.

FIG. 11 is an exemplary ETSI operation bandpass filter in someembodiments. The ETSI operation bandpass filter may be any filtermodule. In one example, the ETSI operation bandpass filter may be filtermodule 716. In various embodiments, the configuration of filter module716 depicted in FIG. 10 meets ETSI emission masks.

In the example depicted in FIG. 11, the ETSI operation bandpass filterincludes a plurality of filters (e.g., a plurality of filter modules1102-1114). Although FIG. 11 is identified as an ETSI operation bandpassfilter, each filter of the plurality of filters may be any kind offilter. In some embodiments, all filters of the ETSI operation bandpassfilter are the same type of filter. In one example, each filter is abandpass filter with a different frequency range. In variousembodiments, each or some of the filters in the ETSI operation bandpassfilter may be different a different type of filter from one or moreother filters types of the FCC operation bandpass filter. In variousembodiments, each of the plurality of filter modules 1102-1114 maycomprise any number of filters.

Similar to the example depicted in FIG. 10, each of the plurality offilters of the ETSI operation bandpass filter is a bandpass filtercentered at 311 MHz and has a different bandwidth. For example, filtermodule 1102 is centered at 311 MHz and has a bandwidth of 7 MHz. Filtermodule 1104 has a bandwidth of 14 MHz, filter module 1106 has abandwidth of 28 MHz, filter module 1108 has a bandwidth of 56 MHz,filter module 1110 has a bandwidth of 112 MHz, filter module 1112 has abandwidth of 224 MHz, and filter module 1114 has a bandwidth of 448 MHz.Those skilled in the art will appreciate that there may be any number offilter modules in the ETSI operation bandpass filter. In one example,each filter of the ETSI operation bandpass filter may have a bandwidthof the pattern depicted in FIG. 11. Further, those skilled in the artwill appreciate that the filters may be at different center frequenciesand/or different bandwidths.

Like the ETSI operation bandpass filter, the ETSI operation bandpassfilter may comprise a plurality of switches S0-S6, each of the pluralityof switches coupled to a filter module. The plurality of switches may becontrolled by the carrier selection signal(s) to engage or disengage(e.g., open or close the switches) to enable or disable one or more ofthe plurality of filter modules 1102-1114.

In various embodiments, the ETSI operation bandpass filter may receive amulticarrier transmit signal. The signal may be provided to each of theplurality of switches. If a switch is open, the signal is blocked frombeing received by related a filter module of the plurality of filtermodules. If a switch is closed, the multicarrier transmit signal isfiltered by the related filter module of the plurality of filtermodules. Any or all of the switches S0-S6 may be controlled by thecarrier selection signal.

Used carriers pass through the ETSI operation bandpass filter to becombined by combiner 1116 while unused carriers of the multicarriertransmit signal are blocked (e.g., attenuated by the coupled filtermodules of the plurality of filter modules). The combiner 1116 providesthe filtered multicarrier transmit signal to other components of the ODU110 and/or an antenna. Those skilled in the art will appreciate that oneor more of the filter module of the ETSI operation bandpass filter maybe coupled to any number of switches or logic circuitry.

FIG. 12 is an exemplary multi-carrier operation bandpass filter in someembodiments. The multi-carrier operation bandpass filter may be anyfilter module. In one example, the multi-carrier operation bandpassfilter may be filter module 716.

In the example depicted in FIG. 12, the multi-carrier operation bandpassfilter includes a plurality of filters (e.g., a plurality of filtermodules 1202-1212). Although FIG. 12 is identified as a multi-carrieroperation bandpass filter, each filter of the plurality of filters maybe any kind of filter. In some embodiments, all filters of themulti-carrier operation bandpass filter are the same type of filter. Inone example, each filter is a bandpass filter with a different frequencyrange. In various embodiments, each or some of the filters in themulti-carrier operation bandpass filter may be different a differenttype of filter from one or more other filters types of the multi-carrieroperation bandpass filter. In various embodiments, each of the pluralityof filter modules 1202-1212 may comprise any number of filters.

Each of the plurality of filters of the multi-carrier operation bandpassfilter is a bandpass filter at a different center frequency. One or moreof the plurality of filters may have a different bandwidth. For example,filter module 1202 is centered at 269 MHz and has a bandwidth of 28 MHz.Filter module 1204 is centered at 297 MHz and has a bandwidth of 28 MHz,filter module 1206 is centered at 325 MHz and has a bandwidth of 28 MHz,filter module 1208 is centered at 353 MHz and has a bandwidth of 28 MHz,filter module 1210 is centered at 283 MHz and has a bandwidth of 56 MHz,and filter module 1212 is centered at 339 MHz and has a bandwidth of 56MHz. Those skilled in the art will appreciate that there may be anynumber of filter modules in the multi-carrier operation bandpass filter.In one example, each filter of the multi-carrier operation bandpassfilter may have a bandwidth of the pattern depicted in FIG. 12. Further,those skilled in the art will appreciate that the filters may be atdifferent center frequencies and/or different bandwidths.

Like the FCC and ETSI operation bandpass filters, the multi-carrieroperation bandpass filter may comprise a plurality of switches S0-S5,each of the plurality of switches coupled to a filter module. Theplurality of switches may be controlled by the carrier selectionsignal(s) to engage or disengage (e.g., open or close the switches) toenable or disable one or more of the plurality of filter modules1202-1212.

Used carriers pass through the multi-carrier operation bandpass filterto be combined by combiner 1214 while unused carriers of themulticarrier transmit signal are blocked (e.g., attenuated by thecoupled filter modules of the plurality of filter modules). The combiner1214 provides the filtered multicarrier transmit signal to othercomponents of the ODU 110 and/or an antenna. Those skilled in the artwill appreciate that one or more of the filter module of themulti-carrier operation bandpass filter may be coupled to any number ofswitches or logic circuitry.

In various embodiments, the multi-carrier operation bandpass filter mayreceive a multicarrier transmit signal. The signal may be provided toeach of the plurality of switches. If a switch is open, the signal isblocked from being received by related a filter module of the pluralityof filter modules. If a switch is closed, the multicarrier transmitsignal is filtered by the related filter module of the plurality offilter modules. Any or all of the switches S0-S5 may be controlled bythe carrier selection signal.

FIG. 13 is a depiction of a multicarrier transmit signal that may befiltered by the multi-carrier operation bandpass filter identified inFIG. 12 in some embodiments. In this example, all switches are closedthereby coupling the plurality of filters of the multi-carrier operationbandpass filter to a path with the multicarrier transmit signal. As aresult, all filters of the plurality of filters are enabled. Thefiltered multicarrier transmit signal is ultimately combined by combiner1302.

Those skilled in the art will appreciate that in order to enable one ormore filters, multiple switches may be enabled. For example, althoughany combination of switches S0-S3 may be on or off, switch S4 may not beset to “on” (e.g., closed) with either switch S0 or S1 set to “on.”Switch S4 can be set with any combination of switches S3 and S4.Similarly, switch S5 may not be set to “on” (e.g., closed) with eitherswitch S2 or S3 set to “on.” Switch S5 can be set with any combinationof switches S0 and S1.

The above-described functions and components can be comprised ofinstructions that are stored on a storage medium such as a computerreadable medium. The instructions can be retrieved and executed by aprocessor. Some examples of instructions are software, program code, andfirmware. Some examples of storage medium are memory devices, tape,disks, integrated circuits, and servers. The instructions areoperational when executed by the processor to direct the processor tooperate in accord with some embodiments. Those skilled in the art arefamiliar with instructions, processor(s), and storage medium.

Various embodiments are described herein as examples. It will beapparent to those skilled in the art that various modifications may bemade and other embodiments can be used without departing from thebroader scope of the present invention. Therefore, these and othervariations upon the exemplary embodiments are intended to be covered bythe present invention(s).

The invention claimed is:
 1. A radio system, comprising: a cable; anantenna; an attenuator having an attenuator first terminal coupled tothe cable and having an attenuator second terminal, the attenuatorconfigured to attenuate transmit signals and receive signals; a firstsplitter having a first splitter first terminal coupled to theattenuator second terminal, and having a first splitter second terminaland a first splitter third terminal; a second splitter having a secondsplitter first terminal coupled to the first splitter second terminal,and having a second splitter second terminal and a second splitter thirdterminal; a first amplifier having a first amplifier output terminalcoupled to the second splitter second terminal, and having a firstamplifier input terminal coupled to receive a first receive signal fromthe antenna; a second amplifier having a second amplifier outputterminal coupled to the second splitter third terminal, and having asecond amplifier input terminal coupled to receive a second receivesignal from the antenna; a third amplifier having a third amplifierinput terminal coupled to the first splitter third terminal and having athird amplifier output terminal; and a filter having a filter inputterminal coupled to the third amplifier output terminal and having afilter output terminal coupled to the antenna, the filter configured toblock at least a portion of the first receive signal and the secondreceive signal from the third amplifier output terminal, the filterfurther configured to pass at least a portion of the transmit signals toreach the antenna.
 2. The radio system of claim 1, wherein theattenuator is a variable attenuator, includes an attenuator controlterminal, and is configured to attenuate the transmit signals and thereceive signals based on a power feedback signal received at theattenuator control terminal.
 3. The radio system of claim 2, furthercomprising a power detector having a detector input terminal coupled tothe filter output terminal and having a detector output terminal coupledto the attenuator control terminal, the power detector configured tomeasure power at the filter output terminal and to generate the powerfeedback signal based on the measured power to control the variableattenuator.
 4. The radio system of claim 1, wherein each transmit signalis a multi-carrier transmit signal, and wherein the filter is configuredto filter unused carriers of the multi-carrier transmit signal.
 5. Theradio system of claim 4, wherein each carrier of the multi-carriertransmit signal is associated with a respective frequency, and whereinthe filter includes a switch and a bandpass filter pair for eachcarrier, each bandpass filter associated with the respective frequency,each switch being enabled or disabled to filter an unused carrier of themulti-carrier transmit signal from reaching the antenna.
 6. The radiosystem of claim 5, wherein each switch is controlled by a carrierselection signal received over the cable.
 7. The radio system of claim1, wherein the cable is a coaxial cable.
 8. The radio system of claim 1,wherein the antenna is a microwave antenna.
 9. A method performed by aradio system, the method comprising: receiving from a cable a firsttransmit signal for transmission by an antenna; attenuating, using anattenuator, the first transmit signal from the cable; splitting, using afirst splitter, the first transmit signal from the attenuator into asecond transmit signal and a third transmit signal; passing the secondtransmit signal to a transmit path; passing the third transmit signal toa receive path; amplifying, using a first amplifier, the second transmitsignal; passing, using a filter, at least a portion of the secondtransmit signal from the first amplifier to the antenna fortransmission; receiving a first receive signal and a second receivesignal from the antenna; amplifying, using a second amplifier, the firstreceive signal; amplifying, using a third amplifier, the second receivesignal; combining, using a second splitter, the first receive signalfrom the second amplifier and the second receive signal from the thirdamplifier to generate a first combined receive signal; passing the firstcombined receive signal to the receive path; splitting, by the firstsplitter, the first combined receive signal into a second combinedreceive signal and a third combined receive signal; attenuating, usingthe attenuator, the second combined receive signal; passing the secondcombined receive signal to the cable; passing the third combined receivesignal to the transmit path; amplifying the third combined receivesignal; and blocking, using the filter, at least a portion of the thirdcombined receive signal before the third combined receive signal reachesthe antenna.
 10. The method of claim 9, wherein the attenuator is avariable attenuator configured to attenuate the transmit signals and thesecond and third combined receive signals based on a power feedbacksignal.
 11. The method of claim 10, further comprising measuring powerat the filter, and using the measured power to generate the powerfeedback signal.
 12. The method of claim 9, wherein each transmit signalis a multi-carrier transmit signal, and the filter is configured tofilter unused carriers of the multi-carrier transmit signal.
 13. Themethod of claim 12, wherein each carrier of the multi-carrier transmitsignal is associated with a respective frequency, and wherein the filterincludes a switch and a bandpass filter pair for each carrier, eachbandpass filter associated with the respective frequency, each switchbeing enabled or disabled to filter an unused carrier of themulti-carrier transmit signal from reaching the antenna.
 14. The methodof claim 13, wherein each switch is controlled by a carrier selectionsignal received over the cable.
 15. The method of claim 9, wherein thecable is a coaxial cable.
 16. The method of claim 9, wherein the antennais a microwave antenna.